Class 2: Intro' to shader writing: RSL (RenderMan Shading Language) Programmable shading - idea by Rob Cook. "Connect the blocks" to hook up shader pieces into complex functionality. Pat Hanrahan formalized the idea into RSL. Overall philosophy of shader-writing: * you'd write them "blind", ie. not knowing when on a surface it gets called * RenderMan will provide detailed neighborhood info. for current shading point * you'd write the shader in ASCII (.sl), compile it, generate a more efficient machine-readable version (.slo) * the shader (.slo file) will be referenced in the RIB file containing the surface that we wish to shade * shaders can be thought of as external (to RIB) shading "plugins" which RenderMan uses during rendering RenderMan specifies five shader types: surface displacement light atmosphere (volume) imager Simplest possible (surface) shader: surface shaderskel() { }/* shaderskel */ surface constant() { Oi = Os; Ci = Os * Cs; } What are Oi, Os, Ci and Cs?
A shader has three sources of data: Variables are of specific types in RSL. N=1 n=2 n=3 n=4. CG Education. Concepts: "Look Development" I was going to post a more advanced (and fun) tutorial today, but I immediately realized that I was talking about a concept called Look Development that not everyone is familiar with, so here's my definition: Look Development (aka "look-dev") is the process, or method, that an artist (or team of artists) goes through to come up with the look of the final imagery for a project. Look-dev also includes figuring out and demonstrating the techniques and tools (aka "the pipeline") that will be used to achieve that goal. At a nuts-and-bolts level, the look-dev artist's job is to examine reference material (or style guides), determine what characteristics need to be duplicated in CG to match the effect, or feel of the project, and come up with a technical method for producing the desired look.
In practice look-dev can be viewed as a three-step, recursive process that goes like this: observation -> execution -> critique -> observation -> execution -> critique -> lather -> rinse -> repeat... MIA Material - Background Information. Introduction MIA_material put to use[1] The mental ray mia_material is a monolithic material shader that is designed to support most materials used by architectural and product design renderings. It supports most hard-surface materials such as metal, wood and glass. It is especially tuned for fast glossy reflections and refractions (replacing the DGS material) and high-quality glass (replacing the dielectric material).
Besides the 'mia material', you can use 'mia material x'. There are a lot of properties to set when using mia materials. Theory Physics MR Shading Model[2] The mia_material primarily attempts to be physically accurate by keeping the track of the light distributed; when light strikes a "real-world" material, part of the light is absorbed, reflected and/or refracted, hence no light magically (dis)appears. Because of this physical correctness Mental Ray generates an image which has an output with a high dynamic range.
Diffuse - diffuse channel (including Oren Nayar "roughness"). 10 key tips for lighting and look development. Cosku Turhan’s 2012 showreel. Below, the Sony Pictures Imageworks Senior Lead Technical Director reveals 10 expert tips for realistic lighting and look development work, drawing examples from the shots above. Photorealism is both my professional speciality and my personal passion. I like to observe the nuances of natural phenomena so that I can trick an audience into forgetting that what they are watching is CG. In simple terms, what we do is make believe, and because we don’t have the tools or computing power to reproduce all of the detail present in nature, we have come up with certain tricks to achieve a similar effect. Here are a few tips technical directors like me use every day to overcome the curse of the ‘CG look’ and to streamline the process of lighting and look development for characters and environments.
A simple look development environment. Keep look dev and final shot lighting separate. 1. 2. No real surface is completely smooth. 3. 4. 5. One of HDR Labs‘ free sIBLs. 6. 7. Part 2: Lookdev and Shader Development. Before getting my hands dirty in Slim networks and actual shader setup, I want to take a moment to talk about pipeline issues and general techniques. Before I started to paint the textures for the Gatling Droid, I did a rough test scene using an HDR image that I took for lookdev purposes. The HDR was acquired using a Manfrotto 303SPH spherical head and a Canon 5dmkII with bracketing controller by Promote.
I took a HDR that was about 24k and did the HDR stitching inside Auto Panno Gigga. I used a downscaled version for lookdev purposes. www.promotesystems.com www.kolor.com/autopano-giga The test scene was a simple plane and a shading ball with known values of completely black, completely white, off white and off black as well as 50 percent grey that I painted inside Mari and then linearized. I came up with the magic number of 2.1 for the intensity of the RMSEnvLight. Basic Setup with RMSEnvLight Let's take quick look at the asset inside Mari. Basic Texture Strategy in Mari $ENTITY_$CHANNEL.
Complex Material Tutorial | Marmoset. By Joe “EarthQuake” Wilson How do I make X material type in Toolbag? I decided to throw together an asset to help explain how the Marmoset Toolbag material system works and display the type of art content I create to mimic various real world material properties. Download the camera asset to follow along and view in full 3D glory inside of Toolbag, here: DOWNLOAD CAMERA ASSET Unzip the asset to your Toolbag directory: X:\Program Files(x86)\MarmosetToolbag ..
\MarmosetToolbag\camera\camera.mesh should be the final path to ensure all files load correctly. Essential Terms: First things first, this tutorial is covering the Marmoset material system and how to achieve the most from your diffuse, normal, specular, and gloss maps while representing a variety of material types. Let’s start by explaining what each map does and how it will relate to the Marmoset material system. Note: Your specular and gloss values apply to dynamic lights as well as the default environment lighting.
Diffuse Map Normal Map. Lookdev MasterClass 2012. Simple description of a gloss map? Specular Color Mapping. Specular Level Mapping. Glossiness Mapping. What does this job requirement mean exactly? Quote: Not if it can be avoided! But more seriously: Depends from the shop, the amount of people on the floor, the pipeline, and what stage things are at. The definition of LookDev is also something that changes slightly depending on where you work. In some places it covers things from RnD to compiling and it relies on a feedback loop, in some others it's in the hand of less technical people (or technically minded artists), and then it's cleaned, refactored and polished for assembly afterwards, redelivered and frozen as much as possible.
The shading process itself is something that can change wildly from place to place. In some other places the granularity of the output stays high all the way through and re-assembly is left to comp pulling together a ridiculous amount of passes, or running a precomp of the elements first. P.S. It can also be taken quite literally and it will make sense. Shader TD and the look development process explained.